1. Field of the Invention
The invention relates to communication techniques with particular applicability to use in the System-on-Chip (SoC) interconnect domain.
2. Description of the Related Art
In order to connect a large amount of Intellectual Property (IP) cores together, Network on Chips (NoC) are increasingly used. The main building blocks of a Network on Chip are the Network Interface (NI), the router or nodes, and the link. The NI(s) provide the access point for the IP cores, routers provide the actual data transport mechanism, and links are used to set up point-to-point interconnections.
With reference to FIG. 1, network architectures can be divided typically into 5 network layers. Layer L1 defines the physical layer such as the link wires L. Layer L2 represents the data link layer, which defines the format of data on the network. Specifically, the data link layer handles the physical and logical connections to the destination of the packet. Layer L3 represents the network layer, which is responsible e.g. for routing. Layer L4 represents the transport layer, which subdivides user-data into network-packets. Finally, layer L5 represents the application layer.
Usual Network on Chip packet formats follow an approach such that interoperability between different IP protocols is not easy to manage and arbitration granularity is usually fixed and common to all the IP cores.
The missing IP protocols interoperability implies the need for using protocol converters when different IP cores need to communicate to each other and coexist in the same system, which results in an overhead in terms of area and latency, paid e.g. in terms of clock cycles required to perform the conversion.
The unique arbitration granularity forces to treat all traffic types generated by the different IP cores in the same way, preventing the possibility of applying different arbitration strategies to different traffic classes, what would allow to guarantee a better quality of service (QoS).
Additionally, there is no error management and transport policy, which support any particular IP protocol, and consequently error conditions cannot be managed in an optimized way.